Intermittent Parasitic Drain

[Aldous]

2005 X5 4.4

When I dont run my car for approximately 4 days (though once as short as 2) it won't start due to a dead battery. It's typically right dead, no interior lights, electric locks etc, no signs of life from the dash when turning the key. When i use the car regularly, couple drives a day, no problems at all, starts up quick with plenty of power etc.

I've had it in the shop, they tested the battery, it passed. Then they did a drain test and after the car goes to sleep the current being drawn drops to either 2 or 20 milliamp (cant remember which but the guy said it was the appropriate amount).

Something is likely waking up on the car at a later time and killing the battery. He mentioned that tracking it down in his shop would be time consuming and expensive so I'm hoping to try and figure it out myself.

The mechanic suggested it could be the FSR as this is a common problem and can cause this. He suggested I check the car occasionally while it's sitting and see if the fan is blowing, also when the climate control is set on auto to listen for quick increases and decreases in blower speed as this is an indication of a failed FSR. I've been reading this site and others and this does seem a likely suspect however i've been unable to catch the car waking up and blowing air, and the fan sounds quite steady when the climate control is on auto. What fuses could be pulled for 4 days to test if the FSR is the culprit?

I've also had a problem with the TCU, it froze and would pair to my phone, the mechanic took it out, replaced it with a new one, it worked. He plugged the old one back in and after the unplugging, it worked fine too (and has been since) however the fact that it locked up says something is wrong and i've read this can drain the battery as well (though not sure it would be intermittent, i would imagine it would be a steady draw and thus traceable). I tried pulling fuses 73 and 74 and the car still died, i think this rules out TCU

Any thoughts on testing? Is there any technology that would allow some continuous monitoring and recording of the power draw overnight for example? i was thinking of a multimeter and a video camera maybe?

Boosting it has been a pain, and with winter coming i really need to solve this.

Any help would be appreciated

[Doru]

I had a similar issue with my e39. I caught the "culprit" by pure accident - after I parked the car, I returned about 1/2 hour later or so to pick up some stuff from the car and the fan was blowing at max speed!!!!!
To pull the fuse - here is a linky that shows different fuses and relay locations. It's for the e39, but e 53 is similar in certain aspects. If it's the FSU, make sure you buy the OEM part - if you want to save some $$$, get the Valeo/Sitronic brand, and make sure it's not made in CPR.

[bcredliner]

Yes, FSRs do fail and are high on the troubleshooting list for a battery drain issue.

In case you need to replace FSR: http://www.xoutpost.com/articles/x5/...nt-bmw-x5.html

Electrical issues are a pain and I think the best way to find a solution is to be sure you are eliminating a potential cause before proceeding with other possible causes. While fuses can be a conclusive test there be other associated fuses. I prefer to disconnect the suspected part so I know it can't draw current whenever I can fairly easily.

Fuse 64 (50A) is for heating and air conditioning. Related fuses are 3 (5A) and 48 (7.5A)
Symptoms of bad FSR can be fan not running, changing speeds, running intermittently or running after key is off, I would expect to find other symptoms indicating a bas FSR.

There are a myriad of other possible causes. Some of the ones that have more frequently been the cause are the phone which you can disconnect. (Noting you had a phone issue--does it tie to when this problem started?). The radiator coolant fan which you should be able to hear. The CD unit or the nav unit which you can disconnect. Also, check all heat/air/fan controls to see if they are working properly.

I would also verify that the testing of the battery included a load test or do one on your own. Auto parts stores will often load test the battery free of charge.

[starbiker99]

I had to replace my battery this summer due to to being drained several times. The culprit was the FSR!!! I have not had an issue since!! (fingers crossed)

[TiAgX5]

Ive read that "auto" mode causes the FSRs to fail sooner, due to limited airflow allowing more heat to build up in the FSR. Anyone else heard of this?

[HEISING]

There are tons of electronic doo dads on your vehicle, the FSR is pretty high on the suspect list.

If you think it may be your FSR, Check out my thread. It may save you some money.

http://www.xoutpost.com/bmw-sav-foru...r-fix-diy.html

Good Luck

[X5Flyboy]

Been there, done that. FSR fur sure. 7 years later, still going strong with no electrical issues in my 2001 X5. But I also have the habit of turning off all electronics before turning off the key. Just as I also roll my all windows down virtually every time I drive my car to keep the window regulators cables flexible and prevent kinking & creating weak spot. Also 7 yrs and counting.

[Aldous]

well thanks for the input, i've pulled the blower fuses and the vehicle is sitting now, in a few days i'll try and fire it up, if it fires up i'll either fix or simply replace the FSR

once i think i have the problem solved i'll get a new battery as even though this one passed the testing, it's now been fully drained around 6 times and the battery was a few years old to begin with.

[TiAgX5]

Originally Posted by X5Flyboy

Been there, done that. FSR fur sure. 7 years later, still going strong with no electrical issues in my 2001 X5. But I also have the habit of turning off all electronics before turning off the key. Just as I also roll my all windows down virtually every time I drive my car to keep the window regulators cables flexible and prevent kinking & creating weak spot. Also 7 yrs and counting.

I do the same, everything off B4 shutdown and window down/up evey 2 or 3 days. over 10 yrs and 170k miles and OE regulators, OE battery lasted over 8 yrs.

[Aldous]

well i pulled fuses 64 and 34 and the battery still died

from the wiring diagram i found at WDS BMW Wiring Diagram System - X5 E53 it looks like fuse 64 is indeed the fuse for the final stage unit.

i guess that rules out the FSU as being the parasitic drain culprit

time to try some different fuses i suppose